Scientists Have Developed Gene-Edited Mosquitoes That Can’t Transmit Malaria

PETER DOCKRILL

25 NOV 2015

There are between 300 and 500 million new cases of malaria each year, with the disease costing as many as 1 million lives annually, but the majority of those cases could one day be avoided thanks to a significant but controversial new innovation developed by researchers in the US.

Gene-edited mosquitoes incapable of transmitting the malaria virus have been successfully developed, and they could ultimately overtake populations of malaria-carrying mosquitoes in the wild.

“This opens up the real promise that this technique can be adapted for eliminating malaria,” said Anthony James, a molecular biologist and geneticist at the University of California, Irvine.

Using the CRISPR gene-editing tool, the researchers introduced an antimalarial DNA element into the germ line of Anopheles stephensi mosquitoes, a major carrier of malaria in Asia. The technique resulted in 99.5 percent of the mosquitoes’ offspring inheriting the gene that prevents malaria transmission.

To measure how widespread the inserted gene element was in the offspring, the researchers also included in their genetic ‘cassette’ a protein that gave their eyes a red fluorescence. That way the scientists could easily figure out that almost all of the offspring generation had inherited the new genetic traits.

While their experimental breed was developed under tightly controlled lab conditions, the end goal is to introduce gene-edited insects into native populations, effecting a gene drive that could ultimately eradicate malaria, due to gene-edited mosquitos overrunning natural specimens.

However, before any field tests can commence, the researchers will conduct more lab work to confirm the efficacy and safety of the malaria-blocking antibodies. The findings are published in PNAS.

“This is a significant first step,” said James. “We know the gene works. The mosquitoes we created are not the final brand, but we know this technology allows us to efficiently create large populations.”

But while such a gene drive holds huge promise for potentially eradicating malaria and ending the misery it causes to so many people, the idea is still very controversial – altering as it would the genetic properties of an entire species.

“[Gene drives] have tremendous potential to address global problems in health, agriculture, and conservation, but their capacity to alter wild populations outside the laboratory demands caution,” concluded the authors of a cautionary study on the technology in Science this year. “Just as researchers working with self-propagating pathogens must ensure that these agents do not escape to the outside world, scientists working in the laboratory with gene drive constructs are responsible for keeping them confined.”